Summary The Korean Air Boeing 747-200, flight number 257 (KAL257), serial number 20652, was on a cargo flight from Anchorage International Airport, Alaska, USA, to John F. Kennedy International Airport, New York, USA. The Lufthansa German Airlines Boeing 747-200, flight number 493 (DLH493), serial number 23622, was operating as a scheduled passenger flight from Vancouver International Airport, British Columbia, to Frankfurt International Airport, Germany. Both aircraft were cruising at flight level 330 and their planned tracks converged approximately two nautical miles east of the JOWIT intersection. Both aircraft were under radar control of the Edmonton Area Control Centre's Bison sector controller. At approximately 1854 mountain daylight time, the Bison sector controller issued turning instructions to both aircraft to avoid a possible collision. The minimum distance between the two aircraft was estimated to have been 1.3 nautical miles horizontally while they were at the same altitude. During their turns, both aircraft received resolution advisories on their traffic alert and collision avoidance systems. DLH493 climbed and KAL257 descended and achieved 900 feet of separation in approximately 10 seconds. The minimum separation required is five nautical miles or 2000 feet. Ce rapport est galement disponible en franais. Other Factual Information The Edmonton Area Control Centre (ACC) comprises a number of Specialties; the Bison sector is one of four sectors located in the Northern High Specialty. The Northern High Specialty was staffed with four controllers, one for each sector. Because of the light traffic at that time of day, no supervisor was scheduled for the Northern High Specialty. The staffing requirement for the Bison sector is a minimum of one controller. Traffic conditions were described as light, and complexity as normal. The Bison sector controller possessed a valid air traffic control licence and medical certificate. He had 20 years of experience as an air traffic controller, with 13 years of experience in instrument flight rules (IFR) procedures. The controller was working day four of a nine-day rotation, with one day off in the last eight days. While working the evening of the August 4, he was notified in writing that he had to extend his shift by four hours, which then ended at 0300 mountain daylight time.(1) The controller obtained seven hours of sleep and began his shift on the day of the occurrence at 1400. Workload during the shift was described as light. He had been working thirty minutes after the dinner break when the incident occurred. Both radar and non-radar procedures are used to control aircraft in the Bison sector. Edmonton ACC procedures require that information on aircraft proceeding into surrounding non-radar sectors be entered into the Northern Airspace Display System (NADS). It is the Bison sector controller's responsibility to confirm that all estimates received and departures authorized for his aircraft have been entered. NADS controllers may assist sector controllers in the provision of non-radar control service to IFR aircraft, but the separation of aircraft remains the sole responsibility of the sector controller. KAL257 was on northern control area track 14 (NCA 14), which begins in a non-radar sector and transits into the Bison sector. The information for KAL257 would have been already entered into the NADS system. DLH493 was transiting from the Bison sector to a non-radar sector north of Bison. This information would have to be entered into the NADS prior to entering the non-radar sector. Once the information for both aircraft is in the NADS, the system has the capability to alert the controller to any conflicts. The Bison sector controller did not recall when DLH493 was entered into NADS and the controller did not receive a conflict advisory from NADS. The NADS system has no ability to record and store events for analysis. The Bison sector controller had his radar display set at the 230 nautical miles scale in order to see his entire sector. When he noticed that the aircraft were in close proximity, he issued an instruction to DLH493 to turn left 40 degrees and then instructed KAL257 to turn left 20 degrees. KAL257 did not respond to the instruction, so the controller queried KAL257, at which time the flight crew acknowledged the controller's instruction. KAL257 then began a right turn, not a left turn as requested by the controller. At the same time, the DLH493 flight crew questioned the controller regarding the left turn because he had traffic on his left. The DLH493 flight crew again queried the controller about the left turn and the controller replied with an instruction to descend to flight level (FL) 310. Shortly after that, the traffic alert and collision avoidance system (TCAS) resolution advisory alert sounded in each aircraft. The DLH493 flight crew responded by climbing to FL335 and the KAL257 flight crew descended to FL326. The time between the first instruction to turn and the time that TCAS manoeuvres were performed was 58 seconds. NAV CANADA does not train its controllers in techniques for resolving losses of separation in time-critical situations. When both aircraft were in the radar-controlled portion of the Bison sector, the controller used the projected track line (PTL) feature of the radar display several times before the incident. The PTL feature extends a line from the target to a distance equivalent to a pre-determined time value. The recorded radar tapes showed the PTL was set to 20 minutes and during the last recorded activation of it, the two lines extending from DLH493 and KAL257 touched. The controller recalled computing a crossing time for an aircraft departing from Yellowknife, Northwest Territories, and had begun to enter DLH493 into NADS in the 20 minutes leading up to the incident. Other than the controller-activated PTL, the radar display system contains no conflict alert software.